Objective The aims of this study were to evaluate bone mineral density (BMD) in patients with juvenile chronic arthritis (JCA), compare them with healthy controls, and assess the effects of disease activity and corticosteroid treatment on BMD. Methods Twenty-eight patients diagnosed with JCA and 45 healthy controls were included in this study. Disease activity was determined by clinical and laboratory evaluation, Articular Disease Severity Score (ADSS), and the Juvenile Arthritis Functional Assessment Report (JAFAR). Bone mineral density of the lumbar spine was measured by dual energy X-ray absorptiometry (DEXA). Results Patients with JCA showed significant decreases in BMD compared with healthy controls. The JCA patients treated with corticosteroids showed significantly lower BMDs than the healthy control group. Age of the patients and age of onset were found to correlate with BMD. Conclusion Our study showed that glucocorticoids were involved in the development of osteoporosis in JCA, with many other factors affecting bone mineralization. We could not demonstrate any relationship between BMD and disease activity, but the study data suggest that early onset disease is also an important factor in the development of osteoporosis in JCA.